Surgical pressure sensitive adhesive sheet product

ABSTRACT

What is disclosed are novel hot melt adhesives having pressure sensitive properties that are comprised of a combination of two acrylic-based copolymers containing the novel monomer 1(2)-methyl-3-oxa-4-oxo-5-aza-nonyl methacrylate, one of the copolymers being a low glass transition temperature (Tg) compolymer and the other a high Tg copolymer and which hot melt adhesives, by means of reversible hydrogen bond formation and dissociation, possess the reversible properties of providing a strong cohesive strength at ambient temperature but also having a melt viscosity at elevated coating temperatures such that it can be used in hot melt coating equipment; a process for making said hot melt adhesives; and a process for making adhesive tapes and bandages using said adhesives.

CROSS REFERENCE

This is a division of application Ser. No. 002,316 filed Jan. 12, 1987,now U.S. Pat. No. 4,762,888 which is a continuation-in-part ofapplication Ser. No. 634,716, filed July 26, 1984, now abandoned.

This invention relates to improved surgical pressure sensitive hot meltadhesives, and to adhesive sheet products such as adhesive tapes andadhesive bandages, utilizing said hot melt adhesives that adhere tohuman skin and remain adherent. In particular, it relates to novel hotmelt adhesives having pressure sensitive properties that are comprisedof a combination of two acrylic-based copolymers, each containing1(2)-methyl-3-oxa-4-oxo-5-aza-nonyl methacrylate as a monomer, one ofthe copolymers being a low glass transition temperature (Tg) copolymerand the other a high Tg copolymer; which hot melt adhesives by means ofreversible hydrogen bond formation and dissociation possess thereversible properties of strong cohesive strength at ambient temperatureand desirable melt viscosity at elevated coating temperatures. Theinvention provides a process for making the hot melt adhesive as well asa process for making adhesive tapes and bandages. This invention alsorelates to the novel compound, 1(2)-methyl-3-oxa-4-oxo-5-aza-nonylmethacrylate, which is used as a monomer to make the adhesives of thisinvention.

BACKGROUND OF THE INVENTION

Hot melt pressure sensitive adhesives are 100 percent solid materials;and therefore, no solvent or water removal is required in coatingoperations. Also, they require a fraction of the energy required bysolvent and water-based systems during coating operations. Hot meltadhesives are applied in a molten state to a backing and are then cooledrapidly with the help of a chill roll. Coating operations can be carriedout at higher speeds with less equipment, lower energy cost, and greatersafety than with solvent or water-based adhesives. Hot melt coatingtechnology offers superior economics to solvent or water-based coating.

There are three classes of hot melt pressure sensitive adhesives:

1. formulated polyethylene copolymers

2. synthetic thermoplastic rubber elastomers formulated with tackifiersand

3. polyacrylates.

To date, the multi-component systems, especially the thermoplasticrubber with additives, have received more attention because of theiravailability, low cost and flexibility of formulation. On the otherhand, the acrylic hot melt adhesives have deficiencies in that theyexhibit an undesirable melt temperature/viscosity profile, unbalancedadhesive properties, and often require additives to modify the acrylicpolymer in order to have acceptable performance.

Many hot melt adhesives presently available are blends of thermoplasticelastomers with plasticizer and tackifier resins derived from naturalresins. These adhesives generally exhibit poor clarity, are discoloredand often irritate the skin, which are undesirable for surgical tapeproducts. Many of the elastomers used in these hot melt adhesivescontain unsaturated chemical bonds, e.g., styrene-isoprene-styrene andstyrene-butadiene block copolymers; these bonds are attacked by oxygenand ultraviolet radiation resulting in loss of adhesive properties.Prior art acrylic hot-melt pressure sensitive adhesives have beenprepared by utilizing nonpermanent intermolecular cross-linking. Aconventional solvent or water-based 100% solids acrylic pressuresensitive adhesive is far from being sufficiently fluid at the coatingtemperatures required for hot melt adhesives.

Hot melt adhesives based on the principle of crystallization to controladhesive viscosity almost always require long sequences of methylenegroups which act to increase the effective molecular weight at lowtemperature. However, a balanced ratio between the crystalline domainsand amorphous regions is essential. At higher crystalline content, anadhesive tends to lose its tackiness due to phase separation whereas ata lower crystalline content an adhesive of low cohesive strength isobtained.

In the past, attempts have been made to produce acrylic-based hot meltadhesives by incorporating 0.5 to 25% by weight of metallic chelatingagents, such as zinc or cadmium salts to an amine-containing copolymer.The thus produced adhesives possess non-permanent, reversible bonds andshowed an increase in Williams Plasticity number from 0.93 to 1.25 mm(U.S. Pat. No. 3,925,282).

Another method found in the patent literature for improving cohesivestrength of acrylic-based hot melt adhesives is blending two copolymers,one copolymer containing a tertiary amine group, and the other has abuilt-in organic acid group. Upon mixing, a reversible ionic bonding isformed. (U.S. Pat. No. 4.045,517).

An improved hot melt pressure sensitive adhesive requires higherWilliams Plasticity number to avoid cold flow. An adhesive for medicalusage generally has higher requirements, such as no skin irritation,clarity, colorless, and higher moduli for lower adhesive transfer toskin. Hot melt adhesives made from amine-containing monomers have hightendency of discoloring, and metallic chelating agents may cause skinirritation. Currently available hot melt pressure sensitive adhesivesexhibit acceptable tack, however, the cold flow, creep resistance andlow modulus properties need improvement.

The novel hot melt pressure sensitive adhesives of this inventionutilize a novel acrylic monomer, 1(2)-methyl-3-oxa-4-oxo-5-aza-nonylmethacrylate, and contain neither organic amine nor acid functionalgroups, nor metallic salts. The hot melt adhesives of this invention arecomprised of a combination of two acrylic-based copolymers, one of whichcopolymers is a low glass transition temperature (Tg) copolymer, whilethe other is a high Tg copolymer. Each of these copolymers uses as acomonomer the novel compound 1(2)-methyl-3-oxa-4-oxo-5-aza-nonylmethacrylate which exists in two isomeric forms, as depicted below:##STR1## For purposes of the present invention, either isomeric form, ora mixture of both, can be used as one of the co-monomers.

The pressure sensitive adhesives of the present invention differ fromthe prior art. Hot melt pressure sensitive adhesive compositions aredisclosed in U.S. Pat. Nos. 4,045,517; 3,925,282; and 4,164,614. Theclosest known art is U.S. Pat. No. 4,045,517 (1977) of Guerin, Hutton,Miller and Zdanowski assigned to Rohm and Haas Company. This patentdiscloses novel polyacrylic hot melt adhesives prepared by blending apolymer having a Tg of -85° to 10° C. with a polymer having a Tg of 20°to 150° C. The hot melt adhesives contain carboxylic acid, sulfonic acidor amine groups.

U.S. Pat. No. 3,925,282 (1975) (Davis, Skoultchi and Fries), NationalStarch and Chemical Corporation, discloses a hot melt adhesivecomposition which possesses the reversible properties of strong cohesivestrength at ambient temperatures and desirable melt viscosity atapplication temperatures and which is prepared by the reaction of anormally tacky acrylic-based random copolymer containing a tertiaryamine-containing monomer with an organic metallic salt comprising atransition metal, tin or lead as the metallic component and an organicacid anion. The random copolymers are capable of forming reversiblecoordinate cross-links on the addition of small amounts of selectedorganic metallic salts.

U.S. Pat. No. 4,164,614 (1979) (W. A. Ames), Eastman Kodak Company,discloses hot melt adhesive compositions comprising terpolymerscontaining 2-ethylhexyl acrylate, N-vinyl-2-pyrrolidone and styrene. Theterpolymers can be applied to tapes or labels.

In addition, U.S. Pat. No. 4,337,325 (1982) (K. Shah), Kendall Company,discloses pressure-sensitive adhesive compositions comprising a blend ofcopolymers consisting of acrylic monomers and vinyl lactam. Thecopolymer adhesive blend exhibits a viscosity less than 100,000 cps at350° F.

STATEMENT OF THE INVENTION

The acrylic hot melt pressure sensitive adhesive of the presentinvention possesses high adhesive strength to human skin and highcohesive strength such that it remains adhered to skin, and yet onvoluntary removal only negligible adhesive transfer to skin occurs. Itis comprised of a combination of two acrylic-based copolymers, eachcontaining a 1(2)-methyl-3-oxa-4-oxo-5-aza-nonyl methacrylate monomer.This monomer is a novel compound, and constitutes another aspect of theinvention.

Since this invention relates to surgical hot melt pressure sensitiveadhesives and more particularly to hot melt pressure sensitive adhesivesand hot melt adhesive-coated products that are adapted to be secured tothe human skin, it is, accordingly, an object of the present inventionto prepare acrylate hot melt pressure sensitive adhesives having goodskin adherence.

A still further object of the present invention is the development of aprocess for making the adhesive. A yet further object of the presentinvention is the development of surgical pressure sensitive adhesivesheet products.

Surgical pressure sensitive adhesive sheet products, as the term isherein used, include any product having a flexible backing and apressure sensitive adhesive coating hereon and includes, although it isnot limited to, such products as adhesive tapes, adhesive bandages,adhesive plasters, adhesive-coated surgical operating sheets,adhesive-coated corn pads, adhesive-coated absorbent dressings, and thelike.

DETAILED DESCRIPTION OF THE INVENTION

The hot melt adhesives of this invention are comprised of a combinationof two acrylic-based copolymers, each of which contains the novelcompound of this invention, 1(2)-methyl-3-oxa-4-oxo-5-aza-nonylmethacrylate. This compound which is used as a monomer herein is a novelcompound that exists in two isomeric forms, as depicted below: ##STR2##For purposes of the present invention, either isomeric form, or amixture of both, can be used. This novel monomer, when incorporated inthe polymer chain, is capable of forming hydrogen bonding inter-orintramolecularly.

The principle of intermolecular or intramolecular hydrogen bonding isused to control adhesive viscosity, cohesive strength, moduli andWilliams Plasticity number.

It has been found that when acrylic monomers are copolymerized with the1(2)-methyl-3-oxa-4-oxo-5-aza-nonyl methacrylate monomer which iscapable of forming H-bonding, there is a significant increase in thecohesive strength of the hot melt adhesive. At room temperature theH-bonding sites function as cross-links between polymer chains. At thecoating temperature, the H-bonds are dissociated or broken, resulting inan adhesive with low melt viscosity suitable for coating on a substrate.The hot melt pressure sensitive adhesives with hydrogen bonding-formingmonomer perform especially well when the adhesive is comprised of ablend of two copolymers both of which contain hydrogen bonding monomer.One copolymer has a lower molecular weight and a glass transitiontemperature (Tg) above 10° C., preferably 25° to 60° C. The othercopolymer comprising the hot melt adhesive has a higher molecular weightand a lower glass transition temperature, lower than -20° C. preferably-30° to -80° C. For convenience the two copolymers will bedifferentiated as being either a "high Tg copolymer" or a low "low Tgcopolymer" for purposes of the present invention.

The preferred hot melt adhesive compositions comprise a blend of:

1. from 15 to 30 parts by weight of a high Tg copolymer having a Tg inthe range of from about 10° C. to about 100° C. containing from 5 to 15parts of hydrogen bond-forming monomer, namely,1(2)-methyl-3-oxa-4-oxo-5-aza-nonyl methacrylate and 85 to 95 parts ofalkyl esters of methacrylic acid, wherein said alkyl group contains 1 to12 carbon atoms. Such alkyl esters include methyl methacrylate, ethylmethacrylate, n-propyl methacrylate, iso-propyl methacrylate, n-butylmethacrylate, isobutyl methacrylate, sec-butyl methacrylate, t-butylmethacrylate, iso-pentyl and cyclohexyl methacrylate. 2. from 70 to 85parts by weight of low Tg copolymer having a Tg in the range of about-20° C. to about -80° C. containing from 5 to 15 parts of hydrogenbond-forming monomer namely, 1(2)-methyl-3-oxa-4-oxo-5-aza-nonylmethacrylate and 85 to 95 parts of alkyl esters of acrylic acid, whereinsaid alkyl group contains 4 to 12 carbon atoms. Such alkyl estersinclude n-butyl acrylate, n-pentyl acrylate, n-hexyl acrylate, n-heptylacrylate, n-octyl acrylate, n-nonyl acrylate, n-decyl acrylate,n-undecyl acrylate, n-dodecyl acrylate and their branched isomers suchas 2-ethylhexyl acrylate.

Especially preferred are hot melt adhesive compositions containing ablend of:

1. from 70 to 85 parts by weight of a low Tg copolymer made from 5 to 15parts by weight of 1(2)-3-oxa-4-oxo-5-aza-nonyl methacrylate monomer and85 to 95 parts by weight of a comonomer selected from one or more of thefollowing:

n-butyl acrylate, ethyl acrylate, methyl acrylate, or 2-ethylhexylacrylate.

2. from 15 to 30 parts by weight of a high Tg copolymer made from 5 to15 parts by weight of 1(2)-methyl-3-oxa-4-oxo-5-aza-nonyl methacrylatemonomer and 85 to 95 parts by weight of comonomer selected from one ormore of the following:

n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate orisopropyl methacrylate.

Polymerization may be carried out by solution, emulsion, suspension orin bulk. For ease of blending, solution polymerization is preferred.Catalysts generally used in polymerizations such as peroxy ester, azocompounds or peroxides are suitable for polymerization. The amount ofcatalyst used is preferably between 0.5 to 8% based on the total monomerweight. The preferred catalysts are benzoyl peroxide, t-butylperbenzoate, t-butyl peroxtoate, t-butyl perpivalate, lauroyl peroxide,dicumyl peroxide, azobisisobutynonitrile, and2,2'-azobis(2,4-dimethyl-valeronitrile).

The moduli and melt viscosity of the hot melt adhesive can be controlledby varying the ratio of the copolymer blend comprising the adhesive tosuit the special product application of the adhesive. Williamsplasticity can be controlled by varying the copolymer blend ratio aswell. To illustrate, an 18% by weight of high glass transitiontemperature (Tg) copolymer blended with 82% by weight of low glasstransition temperature copolymer exhibits a Williams plasticity numberof 1.3 mm, when the copolymer blend is increased to 25% by weight ofhigh glass transition temperature copolymer the Williams plasticitynumber increases to 1.7 mm. The 75/25 copolymer adhesive blend onheating exhibits good melt processing characteristics, the meltviscosity being as follows:

176,000 cp at 300° F.

54,000 cp at 350° F.

21,000 cp at 400° F.

The melt viscosities were determined in a Thermosel viscometer.

The hot melt adhesive of this invention is evaluated by coating theadhesive on a backing material on a hot melt coating machine, makingtapes and wear performance testing of the tapes on human subjects. Forsurgical tape application, various backing materials are used, such ascloth, paper and plastic films. The surgical tape or a first-aid tapeprovided in this invention has the following backing materials. Forabsorbent type backings, they can be wood pulp fibers, rayon, polyester,acetate fibers, cotton fibers and blend combinations such as wood pulpand rayon, and wood pulp and polyester. Plastic backings can bepolyvinyl chloride, polyethylene, polypropylene, Mylar and the like. Thebacking for the tape depends on the application.

The tapes made with the hot melt adhesives of this invention arecompared in wear performance with commercial surgical adhesive tapes.The hot melt adhesive tapes of this invention exhibit higher adhesionand lower adhesive transfer to skin than commercial adhesive tapes.

The invention will be described in greater detail by the followingexamples in which all parts are by weight. As a quantitative aid toevaluating products of the present invention, it has been found helpfulto employ certain empirical tests, which will be described in moredetail.

Williams Plasticity Number--This property is measured by the use of aWilliams Plastometer which is manufactured by Scott Tessters, Inc. andis designed to conform to the standards set by ASTM Method D-926.

Wear Performance Test--Adhesion to Skin, 24-Hour Arm Test, Panel--24Subjects. Procedure--Six to eight 1×3" strips of adhesive rotated sothat each sample is in each position an equal number of times. There areno restrictions on normal activities and bathing habits. At the end of24 hours, adhesion readings are taken. Skin redness, degree of skinstrippage and adhesive left on the skin are noted and recorded. Therating and scoring of adhesion and adhesive transfer are recorded as:

    ______________________________________                                                              Adhesion                                                Adhesion Rating Scale Scoring Scale                                           ______________________________________                                        0 = Adhesive tape off 0                                                       1 = Hanging - 3/4 off 0                                                       2 = Hanging - 2/3 off 0                                                       3 = One or both end flaps up 1/2                                                                    3                                                       4 = One or both end flaps up 1/3                                                                    3                                                       5 = One or more end corners up 1/4                                                                  7                                                       6 = One corner up slightly                                                                          10                                                      7 = Perfect adhesion  10                                                      ______________________________________                                                              Adhesive Transfer                                       Adhesive Transfer Rating Scale                                                                      Scoring Scale                                           ______________________________________                                        0 = No residue        0                                                       0.5 = Trace amount of residue                                                                       1                                                       1.0 = Thin presence of residue                                                                      4                                                       1.5 = Marked, specific amount of residue                                                            4                                                       2.0 = Heavy residue   10                                                      ______________________________________                                    

Data are analyzed on average rating and average score. For example, for24 subjects, all score 7 in adhesion, average adhesion will be 100% andaverage score will be 7.

Modulus Measurement

Rheometrics Dynamic Spectrometer (RDS) is used to determine adhesiveviscoelastic behavior in terms of storage (G') and loss (G") moduli at awide range of oscillation frequency and temperature. RDS is manufacturedby Rheometrics, Inc. in Union, New Jersey.

It uses oscillatory shear over a wide range of frequency, temperature,and amplitude to measure the response or deformation of the polymer. Thedeformation (response) is printed by a Texas Instrument Model 700terminal. Storage, loss and complex moduli are calculated. Also, theratio G" to G', which is tan δ, is computed. Oscillation frequency canbe varied from 0.01 to 500 rad/sec. Temperature can be incrementallyvaried over the range of -150° to 400° C., and temperature and frequencysweeps can be combined. For this invention, the adhesive was examinedunder frequency sweep from 0.1 to 300 rad/sec at 15% strain rate andconstant temperature. Five temperatures, 25°, 36°, 60°, 90° and 120° C.were selected to run each frequency sweep separately. Dynamic storagemodulus (G') and loss modulus (G") were plotted against the frequencyrange at one of the above four temperatures on log-log graph paper. Timetemperature superposition principle is applicable to the adhesivecompositions. A master graph is constructed by shifting modulus curvesof 26°, 60°, 90° and 120° C. to modulus curve of 36° C. (human bodytemperature). The modulus data at the frequency range below 0.1 rad/secare gathered from the measurement at 90° and 120° C. At the frequencyrange between 0.1 to 300 rad/sec modulus data are generated from allfour temperatures.

Example 1 illustrates the method of preparation of1(2)-methyl-3-oxa-4-oxo-5-aza-nonyl methacrylate monomer which is usefulin the preparation of copolymers illustrated in Examples 2-6 which inturn are useful in the preparation of hot melt adhesives and varioussurgical tape products coated with said adhesives as illustrated inExamples 7-11. Instead of preparing the Low Tg copolymer and the High Tgcopolymer separately, and then blending them to make the final adhesivecomposition, it is possible to prepare the final adhesive sequentiallyin the same reactor. This is done by first preparing either one of thecopolymers, then adding the monomers needed for the other copolymer, andreacting them in the same reactor, as illustrated by Example 4 and 5.

EXAMPLE 1 Preparation of 1(2)-Methyl-3-oxa-4-oxo-5-aza-nonylMethacrylate

Butyl isocyanate (167.07 parts), toluene (455.60 parts) and di-t-butylhydroquinone (0.03371 part) were placed in a reaction flask which wasequipped with mechanical stirrer, thermometer, nitrogen inlet anddropping funnel. A solution of hydroxypropyl methacrylate (242.69 parts)and stannous octoate (T-9) (0.3371 part) in toluene (134.27 parts) wasslowly added into the flask over a period of 30 minutes. The temperaturewas maintained at 20° C. After the addition was over, the solution washeated to 50° C. for 7 hrs. or until all the isocyanate group was allconsumed. After the reaction was completed, toluene was removed byapplying vacuum to the flask. The product was a clear liquid with aboiling point of 105° C. at 0.25 mm vacuum. The IR spectrum of theproduct exhibited absorptions at 3380 cm⁻¹ (N-H), 1735 cm⁻¹ ##STR3##1720 and 1570 cm⁻¹ (urethane). The proton nmr spectrum of the compoundin chloroform-d gave absorptions at δ=6.12 (1H), 5.58 (1H) 4.68-5.42(1H), 4.18 (2H), 3.15 (2H), 1.94 (3H) and 0.67-1.62 (7H).

EXAMPLE 2 Preparation of Poly(isobutylmethacrylate/1(2)-methyl-3-oxa-4-oxo-5-aza-nonyl Methacrylate

To a 4000 ml reaction kettle equipped with a condenser, thermometer,nitrogen inlet and mechanical stirrer were added toluene (236.34 parts),monomer mix (98.48 parts) which was prepared by mixing isobutylmethacrylate (623.69 parts) with 32.83 parts of1(2)-methyl-3-oxa-4-oxo-5-aza-nonyl methacrylate of Example 1. Thereaction kettle was heated to 115° C., then 11.82 parts of catalystsolution (8.67 parts of t-butyl peroctoate in 98.48 parts of toluene)were added to the reaction kettle. After polymerizing for 30 minutes at115° C., the remaining 558.04 parts of monomer mix and 63.03 parts ofcatalyst solution were added to the kettle simultaneously over a periodof 3 hrs. After the addition was over, the polymerization was held foran additional 30 minutes at 115° C. The remaining catalyst solution wasthen added dropwise to the solution in 30 minutes. After the additionwas over, the polymer solution was held for 30 minutes at 115° C. Thepolymer solution was cooled to room temperature and discharged from thereactor. The viscosities of the solution were measured at 70°, 150° and250° F. as 170,000, 6,000 and 1,500 cps, respectively. The solventlesspolymer had viscosities of 140,000, 70,000 and 8,000 cps at 300°, 350°and 400° F., respectively. The copolymer had a Tg at 38° C.

EXAMPLE 3 Preparation of Poly(butylacrylate/1(2)-methyl-3-oxa-4-oxo-5-aza-nonyl Methacrylate)

To a 4000 ml reaction kettle equipped with a condenser, thermometer,nitrogen inlet and mechanical stirrer were added toluene 142.6 parts andmonomer mix 166.95 parts which was prepared by mixing butyl acrylate(641.71 parts) with 1(2)-methyl-3-oxa-4-oxo-5-aza-nonyl methacrylate(71.3 parts) of Example 1. The mixture was heated at 83° C. and 28.88parts of catalyst solution (1.78 parts of lauroyl peroxide in 142.6parts of toluene) were added to the flask. After 30 minutes at 83° C.the remaining monomer mixture and 57.76 parts of catalyst solution wereadded at a constant rate over a period of 3 hours at 83° C. After theaddition was over the polymerization was allowed to continue at 83° C.for 30 minutes. The remaining catalyst solution (57.8 parts) was addeddropwise over a period of 30 minutes. The polymerization was continuedfor another 30 minutes and the polymer solution was discharged from thereaction kettle. The polymer solution had a viscosity of 286,000 cps at71° F. and was 68.1% solid. The solvent-less polymer had a viscosity of42,000 cps at 350° F. and Tg at -45° C.

EXAMPLE 4 Sequential Preparation of Poly(butyl acrylate/isobutylmethacrylate/1(2)-methyl-3-oxa-4-oxo-5-aza-nonyl Methacrylate)

To a 1-l four-neck round-bottom flask were placed 100 parts of toulene,36.1 parts of butyl acrylate and 4 parts of 1(2)methyl-3-oxa-4-oxo-5-aza-nonyl methacrylate of Example 1. The reactionvessel was equipped with a mechanical stirrer, condenser, thermometerand nitrogen gas inlet and was heated to 83° C. by a heating bath. Asolution made of 0.134 parts of lauroyl peroxide and 4 parts of toluenewas added to the flask and the temperature was kept at 83° C. for 30minutes. A solution of 204.54 parts of butyl acrylate, 22.72 parts of1(2)-methyl-3-oxa-4-oxo-5-aza-nonyl methacrylate of Example 1, a mixtureof 8 parts of toluene and 0.267 part of lauroyl peroxide were slowlyadded to the flask over a period of 2 hrs. After the addition was over,the polymerization was allowed to continue for 20 minutes at 83° C. Amixture of 8 parts of toluene and 0.267 part of lauroyl peroxide wereadded to the reaction flask over a period of 10 minutes and thepolymerization was continued for 20 minutes. The reaction temperaturewas then raised to 115° C. A solution of 77.962 parts of isobutylmethacrylate, 4.104 parts of 1(2)-methyl-3-oxa-4-oxo-5-aza-nonylmethacrylate of Example 1 and 0.6504 part of t-butyl peroctoate wasslowly added to the polymerization vessel over a period of 40 minutes.After an additional 40 minutes, a catalyst solution of 0.4336 part oft-butyl peroctoate and 28.82 parts of toluene was added rapidly to thereaction vessel. The polymerization was held for an additional 30minutes at 115° C. The polymer solution was discharged from the flask.The viscosity of the solution was 113,000 cps at room temperature. Thesolid hot melt adhesive polymer had a melt viscosity of 31,000 cps at350° F.

EXAMPLE 5 Sequential Preparation of Poly(butyl acrylate/isobutylmethacrylate/1(2)-methyl-3-oxa-4-oxo-5-aza-nonyl methacrylate

To a 500 ml four-necked round-bottom flask were placed 13.86 parts ofdry toluene, 11.79 parts of isobutyl methacrylate and 2.08 parts of1(2)-methyl-3-oxa-4-oxo-5-aza-nonyl methacrylate. The reaction flask wasequipped with mechanical stirrer, condenser, thermometer and nitrogengas inlet and was heated to 110° C. by a heating bath. A catalystsolution made of 0.03 part of t-butyl peroctoate and 2.77 parts oftoluene was slowly added to the flask and the temperature was kept at110° C. for 30 minutes. Then the bath temperature was reduced to 83° C.A solution of 47.14 parts of butyl acrylate, 8.32 parts of1(2)-methyl-3-oxa-4-oxo-5-aza-nonyl methacrylate, 0.1 part of lauroylperoxide and 9.70 parts of toluene were added dropwise to the reactionflask over a period of 4 hours. After the addition was over, thereaction mixture was allowed to stand for 30 minutes the 0.04 partslauroyl peroxide in 4.16 parts toluene was added into the flask. Thepolymerization was held for an additional hour at 83° C. The polymer wasdischarged from the flask. The solid hot melt adhesive polymer had amelt viscosity of 60,000 cps at 350° F. and a Tg at -41° C.

EXAMPLE 6 Hot Melt Adhesive and Tape

Hot melt adhesives suitable for surgical tape applications were obtainedby blending a solution of low Tg copolymer with a solution of high Tgcopolymer. After thorough mixing, the solvent was removed under vacuum.The copolymer solution of Example 3 and the copolymer solution ofExample 2 were physically blended at 50° to 70° C. in a ratio of 75 to25, respectively, based on the percent solids in the solution. Thesolvent was stripped under vacuum. The solid hot melt adhesive had aWilliams plasticity of 1.7 mm. The melt viscosities of the hot meltadhesive were determined with a Brookfield Thermosel Viscometer usingNumber 28 spindle and were 180,000 cps, 50,000 cps, and 20,000 cps at300°, 350°, and 400° F., respectively. The dynamic mechanical propertiesof the adhesive were determined with a Rheometric Dynamic Spectrometer(RDS). The moduli (G' and G") vs frequency data are given in Table 1.The hot melt adhesive was coated on a rayon cloth taffeta surgical tapebacking material on an Accumeter laboratory, bench-top hot melt coater.The coating temperature was 350° F. The hot melt adhesive was coated at1.4 and 1.8 oz/yd², tapes made and wear performance evaluated. Theresults are shown in Table 2. The adhesive of this example was comparedwith commercial DERMICEL* Cloth Tape sold by Johnson & Johnson Products,Inc., Covimax 472 emulsion adhesive sold by Franklin Chemical Industriesand 2074 emulsion adhesive sold by Monsanto Company. The adhesive tapeof this example exhibited excellent wear performance in skin adhesionand adhesive transfer (low).

EXAMPLE 7 Hot Melt Adhesive and Tape

The procedure of Example 6 was used to blend the copolymer solution ofExample 3 and the copolymer solution of Example 2 in a ratio of 77 to23, respectively. The solvent was stripped under vacuum. The solid hotmelt adhesive had melt viscosities of 147,000, 44,000, and 19,500 cps at300°, 350° and 450° F., respectively. The adhesive was coated on rayoncloth taffeta surgical tape backing material on an Accumeter hot meltcoating machine. The coating temperature was 350° F. and the coatingweights were 1.5 and 1.8 oz/yd². The wear performance was excellent inboth skin adhesion and adhesive transfer. See Table 2.

EXAMPLE 8 Surgical Tape Made With Hot Melt Adhesive

The hot melt adhesive of Example 7 was coated on a paper surgical tapebacking material on the Accumeter coating machine. The coatingtemperature was 350° F. and the coating weights were 1.2 and 1.5 oz/yd².The wear performance of the tapes was excellent in both skin adhesionand adhesive transfer. See Table 3. The adhesive of this example wascompared with commercial Micropore Paper Tape sold by 3M Company andDERMILITE* II Paper Tape sold by Johnson & Johnson Products, Inc.

EXAMPLE 9 Hot Melt Adhesive and Tape

The procedure of Example 6 was used to blend the copolymer solution ofExample 3 and the copolymer solution of Example 2 in a ratio of 80 to 20respectively. The solvent was stripped under vacuum. The solid hot meltadhesive had melt viscosities of 148,000, 46,000 and 19,300 cps at 300°,350° and 400° F., respectively. The adhesive had a Tg of -45° C. The hotmelt adhesive was coated at 350° F. on a rayon cloth taffeta backingmaterial at 1.5 and 1.8 oz/yd². The wear performance was excellent inboth skin adhesion and adhesive transfer. See Table 2.

EXAMPLE 10 Surgical Tape Made With Hot Melt Adhesive

The hot melt adhesive of Example 9 was coated on a paper surgical tapebacking material according to the procedure of Example 8. The wearperformance of the tapes was excellent in both adhesion to skin andadhesive transfer. See Table 3.

                  TABLE 1                                                         ______________________________________                                        Moduli vs Frequency of Example 6                                              Frequency                                                                     rad/sec.     G.sup.1 (dynes/cm)                                                                        G.sup.11 (dynes/cm)                                  ______________________________________                                        0.1          2.0 × 10.sup.5                                                                      1.7 × 10.sup.5                                 1            5.2 × 10.sup.5                                                                      3.5 × 10.sup.5                                 10           10.3 × 10.sup.5                                                                     8.5 × 10.sup.5                                 100          2.9 × 10.sup.6                                                                      2.5 × 10.sup.6                                 500          5.8 × 10.sup.6                                                                      6.0 × 10.sup.6                                 ______________________________________                                    

                                      TABLE 2                                     __________________________________________________________________________    Wear Performance of Adhesives on Rayon Cloth Backing                                      Coating         Average                                                                            Adhesive                                                 Weight                                                                             Average                                                                            Adhesion                                                                            Adhesive                                                                           Transfer                                     Adhesive    oz/yd.sup.2                                                                        Adhesion                                                                           %     Transfer                                                                           %                                            __________________________________________________________________________    Example 6   1.4  6.4  95    0.6  15                                           Example 6   1.8  6.3  92    0.6  14                                           Example 7   1.5  6.8  96    0.6  16                                           Example 7   1.8  6.9  100   0.6  17                                           Example 9   1.5  6.7  100   0.6  15                                           Example 9   1.8  6.5  96    0.6  15                                           Control - Covinax 272                                                                     1.8  6.4  95    0.6  18                                           Control - Emulsion                                                            Adhesive 2074                                                                             1.8  6.4  95    0.8  25                                           Control - Solvent Based                                                       DERMICEL ™ Tape                                                                        1.8  5.4  79    0.4  9                                            __________________________________________________________________________

                                      TABLE 3                                     __________________________________________________________________________    Wear Performance of Adhesives on Paper Backing                                            Coating         Average                                                                            Adhesive                                                 Weight                                                                             Average                                                                            Adhesion                                                                            Adhesive                                                                           Transfer                                     Adhesive    oz/yd.sup.2                                                                        Adhesion                                                                           %     Transfer                                                                           %                                            __________________________________________________________________________    Example 8   1.2  6.0  93    0.5  11                                           Example 8   1.5  6.1  95    0.6  14                                           Example 10  1.2  6.0  91    0.5  11                                           Example 10  1.5  6.1  95    0.5  13                                           Control - Micropore                                                           Paper Tape  --   6.3  96    0.4  8                                            Control - Dermilite ™                                                      II Paper Tape                                                                             --   5.8  87    0.4  8                                            __________________________________________________________________________

We claim:
 1. A surgical pressure sensitive sheet product comprising aflexible backing having supported thereon a hot melt pressure sensitiveadhesive composition suitable for application to human skin, which bymeans of reversible hydrogen bond formation and dissociation possessesthe reversible properties of both (i) strong cohesive strength atambient temperature, and also (ii) a melt viscosity at elevated coatingtemperatures such that it can be used in hot melt coating equipment,said composition comprising:A. from about 70 to 85 parts by weight of anacrylic copolymer having a low Tg in the range of from -20° C. to -80°C. comprising:(a) from 85 to 95 parts by weight of an alkyl acrylatemonomer wherein the alkyl group contains 4 to 12 carbon atoms and (b)from 5 to 15 parts by weight of 1(2)-methyl-3-oxa-4-oxo-5-aza-nonylmethacrylate B. from about 15 to 30 parts by weight of an acryliccopolymer having a high Tg in the range of from 10° C. to 40° C.comprising:(a) from about 85 to 95 parts by weight of an alkylmethacrylate monomer wherein the alkyl group contains 1 to 12 carbonatoms and (b) from about 5 to 15 parts by weight of1(2)-methyl-3-oxa-4-oxo-5-aza-nonyl methacrylate.
 2. A surgical pressuresensitive sheet product of claim 1 wherein the alkyl acrylate monomer ofPart A. (a) is n-butyl acrylate, and wherein the alkyl methacrylatemonomer of Part B. (a) is isobutyl methacrylate.